Generally, houses provide an environment appropriate for human life, to serve as dwelling units for human beings. For this, the houses are provided with cooling/heating systems. A representative form of a dwelling in modern society is an apartment complex.
The apartment complex has a multi-floor structure in which a plurality of dwelling units are stacked in a vertical direction from the ground surface. Due to the particularity in that neighboring dwelling units jointly own floors and walls dividing them, the apartment complex has a necessity for a sound-insulating system capable of preventing transmission of noise between the dwelling sites, in addition to having cooling/heating systems.
A floor heating system should be designed to achieve a rapid room heating with low fuel costs and to have a high heat accumulation capacity for maintaining a heated state for a long time without addition of fuel.
The floor heating system is generally constructed by a wet construction method in which a heat radiator is directly buried in concrete slabs by use of a mortar and a dry construction method in which a heat-insulating material is disposed on concrete slabs and in turn, a heat radiator is mounted in the heat-insulating material.
Floor systems having the above heating system may take the form of a conventional floor system in which the heating system is directly constructed in concrete slabs, or a floating floor system in which the heating system is spaced apart upward from concrete slabs. The floating floor system is also called a double floor structure.
Giving a definition of a floor impact sound in association with the apartment complex, it is a noise being transmitted through floors between dwelling units. The floor impact sound has to be reduced as much as possible, and it has been found that the floating floor system is more advantageous to reduce the floor impact sound than the conventional floor system.
In general, an impact sound generated in a floor passes through a sound-insulating sheet prior to being transmitted to floor slabs. The sound-insulating sheet serves to absorb the impact sound, thereby enabling the insulation of noise. However, conventional sound-insulating sheets have a limit to insulate noise because they should be manufactured in consideration of heating effect in addition to sound insulation effect.
Specifically, increasing the weight of the sound-insulating sheet is advantageous to improve sound insulation effect, but may cause problems of excessively increasing heat-insulation and heating costs. On the other hand, reducing the weight of the sound-insulating sheet is suitable to improve heat insulation effect, but has a problem of deterioration in sound insulation effect.
Further, in the case where the sound-insulating sheet is configured to have a relatively thick thickness for the sake of improving sound insulation effect, there is the risk of rolling of the floor by walking load because of characteristics of the sound-insulating sheet that is made of a flexible material for the absorption of an impact.
Korean Patent Laid-open Publication No. 2004-0071641 discloses a sound-insulating type double floor structure comprising: a plurality of floor supporting panels installed above a base floor at a predetermined height level by use of a group of supporting legs installed through elastic prop members; and a finishing material formed on the supporting panels. The disclosed conventional double floor structure has a feature in that a hardboard or high-density fiberboard having a bending strength of 35˜50 (N/mm2), bending young's modulus of 4000˜5000 (N/mm2) and density of 0.8˜1.2 (g/cm3) is installed between the floor supporting panels and the finishing material. However, it will be appreciated that the conventional double floor structure has no relation with the present invention dealing with a plurality of impact-absorbing materials having different densities from each other.